/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

using System;
using System.IO;
using System.Threading;

namespace DotnetPark.NLucene.Store
{
	/// <summary>
	/// An interprocess mutex lock.
	/// </summary>
	public abstract class Lock
	{
		/// <summary>
		/// Creates a new lock.
		/// </summary>
		public abstract bool Obtain();

		///<summary> Release exclusive access. </summary>
		public abstract void Release();

		///<summary> Utility class for executing code with exclusive access. </summary>
		public abstract class With 
		{
			private Lock _lock;
			private int sleepInterval = 1000;
			private int maxSleeps = 10;
    
			///<summary> Constructs an executor that will grab the named _lock. </summary>
			public With(Lock lck) 
			{
				this._lock = lck;
			}

			///<summary> Code to execute with exclusive access. </summary>
			protected abstract Object DoBody();

			///<summary> Calls {@link #doBody} while <i>_lock</i> is obtained.  Blocks if _lock
			/// cannot be obtained immediately.  Retries to obtain _lock once per second
			/// until it is obtained, or until it has tried ten times. </summary>
			public Object Run()
			{
				bool locked = false;
				try 
				{
					locked = _lock.Obtain();
					int sleepCount = 0;
					while (!locked) 
					{
						if (++sleepCount == maxSleeps) 
						{
							throw new IOException("Timed out waiting for: " + _lock);
						}
						try 
						{
							Thread.Sleep(sleepInterval);
						} 
						catch (ThreadAbortException e) 
						{
							throw new IOException(e.ToString());
						}
						locked = _lock.Obtain();
					}

					return DoBody();
	
				} 
				finally 
				{
					if (locked)
						_lock.Release();
				}
			}
		}
	}
}
